1. Field of the Invention
The present invention relates to a liquid forced-feed apparatus for feeding a liquid, such as water, hot water, fuel, etc., under pressure using high-pressure steam or compressed air as the motive fluid. The liquid forced-feed apparatus of the present invention is particularly suitable for use as an apparatus collecting condensate generated in a steam piping system, and then sending the condensate to a boiler or a waste heat recovery system.
1. Description of the Prior Art
The condensate generated as a result of condensation of steam in a steam piping system, or various other types of equipment using steam, in most cases still has a considerable quantity of heat. Therefore it has been a widespread practice to use a condensate recovery system for effective utilization of this thermal energy, by collecting the condensate having a large quantity of heat in a liquid forced-feed apparatus and sending the collected condensate to the boiler or the waste heat recovery system, for effective utilization of the stored thermal energy.
The liquid forced-feed apparatuses used in prior art condensate recovery systems collect the condensate in a hermetic vessel, and introduce a high-pressure working or motive fluid, such as steam, compressed air, or other fluids, into the hermetic vessel by operating a change-over valve. The liquid forced-feed apparatuses discharge the condensate from inside of the hermetic vessel under the pressure of the working fluid and at the same time supply the condensate to a condensate recovery section.
This type of liquid forced-feed apparatus has been disclosed, for instance, in Japanese Utility Model Publication No. 37-22378.
The liquid forced-feed apparatus described above will be explained with reference to FIGS. 1 and 2. FIG. 1 is a general perspective view, partly sectioned, of the liquid forced-feed apparatus of the prior art. FIG. 2 is an enlarged sectional view of a valve section of the liquid forced-feed apparatus of the prior art. In these drawings, reference numeral 100 refers to a liquid forced-feed apparatus. The liquid forced-feed apparatus 100 incorporates a float 120 and a working steam inlet valve 110, which are built in a hermetic vessel 101.
The hermetic vessel 101 is provided with a forced-feed liquid inflow port 102 and a forced-feed liquid outflow port 103, which are fitted with check valves 105 and 106 respectively. The check valve 105 is mounted in a direction allowing the liquid to flow into the hermetic vessel 101, while the check valve 106 is mounted in a direction allowing the liquid to be discharged out from the hermetic vessel 101.
In the top of the hermetic vessel 101 are formed the working steam inlet port 108 and the working steam outflow port 109, where, as shown in FIGS. 1 and 2, a working steam inlet valve 110 and a working steam discharge valve 111 are mounted. Here, the working steam inlet valve 110 and the working steam discharge valve 111 are opened and closed by moving the valve lifting rods 112 and 113 up and down. The working steam inlet valve 110 is opened when the valve lifting rod 112 is raised, while the working steam discharge valve 111 is closed when the valve lifting rod 113 is raised. The valve lifting rods 112 and 113 are connected in parallel by a connecting plate 115. The working steam inlet valve 110 and the working steam discharge valve 111 are simultaneously opened and closed by moving the connecting plate 115 up and down.
In the prior art liquid forced-feed apparatus 100 the forced-feed liquid inflow port 102 is connected to a steam load (a condensate generating section), via the check valve 105, and the forced-feed liquid outflow port 103 is connected to an apparatus using or recovering waste heat, via the check valve 106. The working steam inlet port 108 is connected to a high-pressure steam source, thereby providing a working fluid. In the liquid forced-feed apparatus 100, when no condensate is present in the hermetic vessel 101, the float 120 is in the lower position, and the connecting plate 115 is down. Therefore, in the working steam inlet valve 110 the valve lifting rod 112 lowers, so that ball valve body 122 mounted on the top end of the valve lifting rod 112 seats on the valve seat 123 to thereby close the opening. On the other hand, in the working steam discharge valve 111, the circular valve head 127 at the top end of the valve lifting rod 113 moves away from the valve seat 128, to thereby open the working steam outflow port 109.
If condensate is generated in the steam load connected to the liquid forced-feed apparatus 100, the condensate flows into the hermetic vessel 101 via the check valve 105 and accumulates in the vessel 101. As the amount of the condensate increases, the float 120 rises. With the rise of the float 120, one end of the arm 118 also rises. If the arm 118 goes up over a specific level, a snap mechanism 140 turns over to raise the rod 121, thereby raising the connecting plate 115. When the connecting plate 115 is raised, the valve lifting rod 112 mounted to the connecting plate 115 in the working steam inlet valve 110 rises to move the valve head 122 away from the valve seat 123, thereby opening the working steam inlet port 108. In the liquid forced-feed apparatus 100, the working steam flows through the opening of the valve seat 123 and through a gap between the valve lifting rod 112 and the valve case 130, being ejected downwardly through the opening provided in the lower end of the valve case 130. At this time, the working steam discharge valve 111 is in a closed position, and therefore the pressure in the hermetic vessel 101 increases to force out the condensate through the liquid outflow port 103. In this liquid forced-feed apparatus 100, the working steam is emitted downwardly from the lower end of the valve case 130 as described above, and therefore most of the working steam is forced into direct contact with the liquid accumulated in the hermetic vessel 101.
In the prior art liquid forced-feed apparatus, because the steam as a working fluid is directly ejected in a direction toward the liquid in the hermetic vessel 101, the working fluid partly is ejected directly into the liquid in the hermetic vessel 101. Steam, when used as the working fluid, therefore is ejected and flows into the cooler liquid, resulting in the steam being condensed. Therefore, the pressure in the hermetic vessel takes time before increasing to a high enough level to force feed the liquid from the hermetic vessel 101, because the steam pressure is reduced by condensation caused by contact of the steam with the cooler liquid. Consequently time is required for liquid to be fed from the hermetic vessel 101.